Process for the manufacture of fibers from high molecular weight linear polyethylene terephthalate

ABSTRACT

THE INVENTION PROVIDES AN IMPROVEMENT IN THE MANUFACTURE OF FIBERS OF HIGH MOLECULAR WEIGHT LINEAR POLYETHYLENE TEREPHTHALATE HAVING A SPECIFIC VISCOSITY BELOW 650. THE TOW OF FILAMENTS IS TREATED, PRIOR TO OR AFTER DRAWING, WITH A LUBRICATING EMULSION CONTAINING A POLYSILOXANE-POLYGLYCOL ETHER AND KNOWN SMOOTHING, FILAMENT BONDING AND ANTISTATIC TEXTILE AUXILIARIES WHEREBY WELDINGS OF THE FILAMENTS ARE AVOIDED WHEN THE CABLE IS CUT INTO STAPLE FIBERS IN THE CONVERTER.

United States Patent PROCESS FOR THE MANUFACTURE OF FIBERS FROM HIGH MOLECULAR WEIGHT LINEAR POLYETHYLENE TEREPHTHALATE Wolfgang Burghardt, Bobingen, and Hans-Otto vom Orde, Gogingen, Germany, assignors to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Bruning, Frankfurt am Main, Germany No Drawing. Filed Aug. 25, 1971, Ser. No. 174,926

Claims priority, application Germany, Aug. 26, 1970, P 20 42 298.4 Int. Cl. B29h 21/04 US. Cl. 264-130 Claims ABSTRACT OF THE DISCLOSURE The invention provides an improvement in the manufacture of fibers of high molecular weight linear polyethylene terephthalate having a specific viscosity below 650. The tow of filaments is treated, prior to or after drawing, with a lubricating emulsion containing a polysiloxane-polyglycol ether and known smoothing, filament bonding and antistatic textile auxiliaries whereby weldings of the filaments are avoided when the cable is cut into staple fibers in the converter.

The present invention relates to a process for the manufacture of fibers from high molecular weight linear polyethylene terephthalate by melt spinning, lubricating, drawing, crimping in the stufiing chamber, and cutting the tow.

In the known manufacture of fibers from polyethylene terephthalate a tow, i.e. a thick bundle of endless filaments spun from the melt, is mechanically transformed into staple fibers by cutting or tearing.

When the tow is cut in the converter, for example a Rieter type converter, the individual capillaries of the cable are welded together under the nip pressure, especially in the case of a tow of low molecular weight polyethylene terephthalate filaments having a specific viscosity below 650. The material leaving the converter and contaminated by Weldings must then be passed repeatedly through the draw frame in order to eliminate as far as possible the Weldings, to separate the fibers from one another and to bring them in parallel position.

The present invention provides a process for the manufacture of staple fibers from polyethylene terephthalate according to which the tow of polyethylene terephthalate filaments is cut into staple fibers in a converter without filaments being welded together.

To this effect the tow of filaments of polyethylene terephthalate having a specific viscosity of up to 650 is lubricated prior to crimping in the stufiing chamber in an immersion process with an aqueous emulsion, the nonaqueous portion of which consists of 60 to 80% by weight, preferably 6575% by weight, of a polysiloxane-polyglycol ether of the general formula y Zy-H B G ]u[ Z 4 ]mi( 3)2 i ]x[ 2 4 ]m[ 3 ]nO yHZy-H in which n stands for 0 to 18 m stands for 15 to 20 x stands for 12 to 20 and y stands for 3 to 7,

and of 40 to 20% by weight, preferably 35 to 25% by weight, the percentages being calculated on the nonaqueous portion of the emulsion, of known smoothing, filament-bonding and antistatic textile auxiliaries in a manner such that after lubrication the two is coated with 0.1 to 0.4% by weight, preferably 0.1 to 0.27% by weight, calculated on the treated tow, of lubricant and 60% of 3,803,284 Patented Apr. 9, 1974 the applied lubricant, calculated on the dry substance of the coating, consist of polysiloxane-polyglycol ether and 40% by weight consist of known smoothing, filamentbonding and antistatically active components, and after lubrication the treated tow is cut in the converter into staple fibers.

According to a special embodiment of the process of the invention the aqueous lubricating emulsion having a strength of 1 to 2% by weight has a pH value in the range of from 8.0 to 9.5, more preferably 8.5 to 9.0.

According to a further preferred embodiment of the process of the invention the lubricant is applied to the tow prior to drawing the melt spun filaments.

The polyethylene terephthalate is spun from the melt with the aid of known devices and the individual filaments are combined to a tow of up to 1 million dtex. or more. The tow is drawn on known devices. Prior to or after drawing, but in any case prior to crimping in the stuifing chamber, the lubricating emulsion containing the specified components is applied to the tow which in then cut into staple fibers in the converter.

The polysiloxane-polyglycol ethers used according to the invention are commercial products which consist of 40-48% by weight of organo-silicium units and 60 to 52% by weight of polyglycol units. They have a silicium content in the range of from 7 to 8.5% by weight. They are available in the form of products of 90 to 98% strength which contain water, small amounts of the materials from which they are made, i.e. alkyl polysiloxane and ethylene glycol or propylene glycol, and organic ammonium bases as stabilizer.

The nonaqueous portion of the aqueous emulsion used should contain 60 to by weight of the polysiloxanepolyglycol ether. If the ether portion falls below 60% by weight, more and more troubles arise during the cutting of the tow into staple fibers and an increasing number of filaments are Welded together in the Rieter converter used in worsted yarn spinning. Weldings do also occur when the proportion by weight of polysiloxane-polyglycol ether in the applied coating of lubricant is below 60%.

On the other hand, the proportion of polysiloxane-polyglycol ether in the nonaqueous portion of the emulsion should not be noticeably above 80% by weight, since otherwise the antistatic properties and the smoothness of the tow and the fibers made therefrom are not satisfactory for the further working up. The remaining proportion of the nonaqueous proportion of the emulsion is composed of the usual smoothing, filament-bonding and antistatically active textile auxiliaries.

After drying, the tow contains 0.1 to 0.4% by weight, preferably 0.1 to 0.27% by weight of lubricant consisting of 60% by weight of polysiloxane-polyglycol ether and 40% by weight of known smoothing, filament-bonding and antistatically active constituents. With an amount of polysiloxane-polyglycol ether below 0.06% by weight, a cutting of the cable into staple fibers without Weldings is not possible, whereas with a content of polysiloxanepolyglycol ether above 0.24% by weight too large an amount of lubricant is abraded and involves trouble in textile spinning.

The amount of lubricant applied to the tow is determined by quantitative extraction according to DIN 54,278. The silicium content of the extract is determined analytically and used to calculate the content of polysiloxane polyglycol ether.

By applying the polysiloxane-polyglycol ether in the form of an aqueous emulsion the tow of polyethylene terephthalate capillaries is thoroughly wetted and acquires a sufficient adhesiveness in the treatment following lubrication. The lubrication has no influence whatsoever on the electrostatic properties. It is, therefore, necessary to add to the emulsion antistatically active agents and smoothing agents. The lubricant according to the invention has a pH value in the range of from 8.0 to 9.5, preferably 8.5 to 9.0. The weak basicity is adjusted by means of organic ammonium bases, for example mono di-, or triethanolamine which serve as stabilizers, and may be regulated additionally by the addition of ethoxylated dodecyl-ammonium.

The special advantage of the lubricating coating according to the invention resides in the separating effect of polysiloxane-polyglycol ethers. The usual lubricants do not have this property of polysiloxane derivatives. The separating effect of the emulsifiable polysiloxane-polyglycol ethers could not have been foreseen. It was surprising that such a favorable eflect could be obtained in the processing of tows in converter spinning.

A tow of polyethylene terephthalate fibers treated according to the invention leaves the nippers of a converter with faultless diagonal out even if a plurality of tows, one lying above the other, having a total titer of 1,000,000 (200,000 to 400,000 individual capillaries) is passed trough the converter. As compared therewith, a tow having a usual titer of 320,000 dtex., which has been coated with the same amount of lubricant but does not contain a polysiloxane compound has nipped and welded edges when it leaves the converter. In worsted yarn spinning such a tow must be again treated with a lubricant before it passes the converter and/or the fibers should be combed repeatedly. This complicated mode of operation with extra work will become superfluous when the tow is treated with a polysiloxane-polyglycol ether. Further processing of the fibers into a thread and washing out of the lubricant before dyeing into a thread and washing out of the lubricant before dyeing do not present dilriculties.

Polyethylene terephthalate filaments having a specific viscosity above 650 are welded to a minor extend only, so that they may be cut into staple fibers according to known methods in the converter.

The following examples illustrate the invention, the percentages being by weight unless otherwise stated.

EXAMPLE 1 A drawn tow consisting of 80,000 individual polyethylene terephthalate filaments having a specific viscosity of 620 and a titer of 4.5 dtex., was continuously treated, prior to crimping, with a lubricant. The humidity was squeezed off to a content of about by weight and the tow was dried. The lubricant was contained in a trough made of stainless steel, into which the tow was immersed over a length of 4.5 meters, the running speed being 70 meters per minute. Wetting with the lubricant was effected under tension, the lubricant had a temperature of 26 C.

The applied lubricant had a pH value of 8.5 and consisted of (6) 98.25% of softened water (German hardness 1") Constituents (1) to (4) were the active ingredients of commonly used textile auxiliaries which have a favorable influence on the electrostatic properties (1,2) and smoothness (3,4) of the tow of polyethylene terephthalate. All constituents were introduced into water having a temperature of 45 C. With stirring at a speed of about 100 revolutions per minute, an oil-in-Water emulsion was prepared which was cooled to 26 C. Immediately after the treatment with the lubricant, the wet tow was crimped in the stutfing chamber.

The tow was coated with 0.2% of anhydrous lubricant, calculated on the weight of the tow. An analysis of an extract according to DIN 54,278 indicated a silicium content of 4.8%, corresponding to a content of polysiloxanepolyglycol ether in the coating of the tow of 62.3% by weight.

The tow was stored in containers for 24 hours at room temperature in an atmosphere with 50% relative humidity. After the transport to worsted yarn spinning 3 tows, one each from 3 containers, having a total titer of 960,000 dtex. were passed into the converter. On passing through the nippers welded edges were not formed and an electrostatic charge was not observed. The tow could be further processed into a thread and dyed without interruption.

COMPARATIVE EXAMPLE 1 A cable as specified in Example 1 was treated with an emulsion containing the usual textile auxiliaries and having a pH of 7.5. The emulsion was composed of 1) 0.4% of the sodium salt of N-lauroyl sarcoside (2) 0.31% of dodecyl-ammonium hydroxide and 20 moles of ethylene oxide (3) 0.71% of stearic acid ester of 1,4-butane-diol and 7 moles of ethylene oxide (4) 0.4% of highly refined mineral oil of 1.5 Engler (5) 98.18% of softened water (German hardness 1).

The tow was coated with 0.25% of lubricant. The further processing was analogous to that described in Example 1, i.e. three tows, one each from 3 containers, which had been coated with a lubricant without polysiloxane-polyglycol ether, were cut in the converter. The cutting edges of the material leaving the converter were welded together. Tests of the purity of the combed maaterial indicated fiber ends which were not separated, fractions of fibers and heterogeneously distributed polyethylene terephthalate particles. The material could not be spun into a roving on the ring spinning machine.

EXAMPLE 2 The lubricant used had a pH of 9.0 and consisted of the following constituents:

(1) 0.14% of dodecyl ammonium hydroxide and 20 moles of ethylene oxide in the form of a 50% aqueous solution (2) 0.60% of emulsifier/ester mixture (3) 1.25% of polyalkylenesiloxane polyglycol ether having a silicium content of 7.8%

(4) 98.01% of softened water (German hardness 1) Constituent (1) was an antistatically active substance and constituent (2) a smoothing agent and consisted of 5 parts by weight of the reaction product of commercial stearic acid with 5 moles of ethylene oxide, 4 parts by weight of butyl stearate and 1 part by weight of stearyl stearate.

To prepare the lubricant the necessary amount of water having a temperature of 40 to 45 C. was first placed in the reaction vessel and constituents (l) to (3) were successively introduced while stirring at a speed of about revolutions per minute. The emulsion obtained was cooled to 23 C. and a tow as specified in Example 1 but having a specific viscosity of 490 was treated with the emulsion as described.

The extraction according to the standard description yielded 0.3% of dry mixture of lubricant containing 0.18% of polysiloxane-polyglycol ether, calculated on the weight of the tow.

The treated tow was stored for 24 hours in containers at room temperature and 50% relative atmospheric moisture. After arriving at a worsted yarn spinning mill, 3 tows, one each form 3 containers, having a total titer of 960,000 dtex. were passed into the converter. Cutting in the converter did not involve welding at the cutting edges and an electrostatic charge was not observed. The combed material was free from unseparated fiber ends,

fiber fractions and polyethylene terephthalate particles. After leaving the converter the material can be further processed immediately into rovings and thread and dyed.

COMPARATIVE EXAMPLE 2 A drawn cable consisting of linear polyethylene terephthalate having a specific viscosity of 780 and consisting of 80,000 individual filaments having a titer of 4.0 dtex. was continuously treated, prior to crimping, with the lubricant specified in comparative. Example 1 and having a pH of 7.5. The lubricant did not contain a polysiloxane-polyglycol ether. The emulsion was applied as described in Examples 1 and 2. After drying the tow contained 0.2% of anhydrous lubricant.

The tow was further treated as described above, i.e. three tows (specific viscosity 780) the applied lubricant of which did not contain a polysiloxane-polyglycol ether, were cut in the converter. Owing to the relatively high specific viscosity neither welded edges not an electrostatic charge were observed. The combed material was free from weldings and could be immediately processed into yarn and dyed.

What is claimed is:

1. In the process for the manufacture of staple fibers of high molecular weight linear polyethylene terephthalate by spinning from the melt, lubricating, drawing, crimping in the stutfing chamber and cutting the tow into staple fibers in a converter, the improvement of preventing the staple fibers from welding together in the converter which comprises treating my immersion the tow of polyethylene terephthalate filaments having a specific viscosity of up to 650, prior to crimping in the stuffing chamber, with an aqueous emulsion the nonaqueous portion of which consists of 60 to 80% by weight of a polysiloxaneglycol ether of the general formula n stands for 0 to 18 m means 15 to 20 x is 12 to 20 y is 3 to 7 and 40 to 20%, calculated on the nonaqueous portion of the emulsion, of known smoothing, filament-bonding and antistatically active textile auxiliaries, after the treating by immersion the treated tow having a coating of 0.1 to 0.4% by weight, calculated on the treated tow consisting of by weight, calculated on the dry content of the coating, of polysiloxane-polyglycol ether and 40% by weight of known smoothing, filament-bonding and antistatically active constituents, and cutting the tow into staple fibers in the converter wherein the treating prevents the fibers from welding together.

2. The process of claim 1, wherein the aqueous emulsion used for treating contains to by weight of the polysiloxane-polyglycol ether and 25 to 35% by weight of the known textile auxiliaries.

3. The process of claim 1, wherein the emulsion used for treating the tow has pH in the range of from 8.0' to 9.5.

4. The process of claim 1, wherein the two is treated with the treating emulsion prior to drawing.

5. The process of claim 1, wherein the tow is treated with the treating emulsion after drawing.

References Cited UNITED STATES PATENTS 3,336,428 8/1967 Waler et al. 264- 3,472,729 10/1969 Sterman et al 2-64-175 3,548,047 12/1970 Jones et al. 264210F 3,511,677 5/1970 Strohmaier et al. 264-210 3,632,715 1/1972 Gowdy et a1 264--210 3,433,008 3/1969 Gage 57-l53 3,452,132 6/1969 Pitzl 264-210 F 3,620,821 11/1971 Johnson 1l7l61ZA 3,639,154 2/1972 Sawa et al. 117-7 3,668,001 6/ 1972 Hosokawa et al. 117161ZA JAY H. WOO, Primary Examiner US. Cl. X.R.

2875 WT; 117139.5 A, 161 ZA; 26415l, 210 F 

650. THE TOW OF FILAMENTS IS TREATED, PRIOR TO OR AFTER DRAWING, WITH A LUBRICATING EMULSION CONTAINING A POLYSILOXANE-POLYGLYCOL ETHER AND KNOWN SMOOTHING, FILAMENT BONDING AND ANTISTATIC TEXTILE AUXILIARIES WHEREBY WELDINGS OF THE FILAMENTS ARE AVOIDED WHEN THE CABLE IS CUT INTO STAPLE FIBERS IN THE CONVERTER. 